1972 Cb350 that has sat for 20 years problems

[Teddyjo]

Hello guys to start I am a 21 year old college student who has just inherited a 1972 Honda CB350 from my father. It has sat idle in a garage for the past 20 years and i recently picked it up to begin an long and arduous restoration process. So far i have actually mangaged to get the bike semi running despite my extreme lack of knowlegde in motorcycles but I need help on a few things to get it running at full potential.


Things I have done: Derusted the gas tank, purchased pretty much mint condition carbs, new petcock, oil change, new battery, got rid of the nest some creature made in the battery compartment (dunno where the old battery went lol), new plugs.


Main Problem: When cold the bike starts up but the left cylinder gives a bit of a spudder/backfire giving it gas corrects it temporarily. I can ride it at this point. Then after a few minutes the bike seems to get unusually hot and begins to bog down and eventually wont start anymore. The carbs are set to spec using the OEM shop manual I have. I just cant figure out why i cant keep it stable. Also I have read many people state check the points but im not sure what the points are lol.


Other smaller problems: Blinkers dont blink (from research on the forums i think i need a new blinker module), horn doesnt work, electric start doesn't work (kick starting in 100 degree weather sucks), and shifter seems very stiff and gear changes arent very smooth (difficult to find neutral).
I appreciate any and all help you guys can give me. I can't wait to pay off my $50k in student loans and actually turn the bike into a beautiful cafe style racer. Thanks again.


TLDR - 39yr old cb350 starts, gets hot, then bogs down

 

[blueandy]

the points are right above your left spark plug. there should be a cover(would be factory black if in good condition) with two small phillips heads. take the screws out and there you have it points. i am no genius when it comes to points i just know how to gap them, which on my cb360 after you gap em you have to check the time, also very easy although hard to explain. there will be someone on here that could explain alot better than I, but you might want to check the search engine at the upper left corner of the site, these problems shouldnt be anything major.

 

[djelliott]

The fact that it sat for 20 years and with little knowledge you got it running I'd say is a very good sign. The problems you explained are very common as well. A few things to check and adjust/repair:


As stated the points. After 20 years I'd just get a new set of points and condensers and start fresh. You can get them for pretty cheap. It's a bit of a dance to get them set right when your new to it, but it's not impossible.


Coil wires. Unscrew the spark plug caps and make sure they're making good contact. You can cut off about a quarter inch and reattach them to be sure.


Carbs. Be absolutely sure they're clean. Take them off, spray out all of the jets and passages with carb cleaner and compressed air. Get rebuild kits if you can (still pretty cheap) and start fresh there too.


Verify that you carb handlers aren't leaking. you do so by running the bike and spaying a bit of started fluid on them. If your idle ticks up a bit, they're leaking.


Over all, you've got yourself a solid platform to begin with. These bikes are great and parts are plentiful and for the most part, affordable. Good luck and don't be afraid to ask questions.

 

[djelliott]

BTW, welcome to the forum.

 

[teazer]

DJ covered most of the points (all puns intended) The electrics are probably corrosion in the switches and connectors.

An old trick is to spray WD40 int the switch from any and every angle and work it back and forth for a few minutes. Sometimes that's enough to get them to work. If not, carefully strip the switch block taking lots of pictures on the way and clean all the contacts with a scotchbrite pad and apply a little dielectric grease from Radio Shack.

Pull all the connectors apart ONE AT A TIME, clean them and apply dielectric grease.

Clean the battery ground connection as well. Electrons have a hard time getting through rust. Cleanliness is your friend.

You probably still have some garbage in one or more carb circuits. I like to strip both carbs together and I use a can of spray carb cleaner to blow through one passage at a time and I compare one carb to the other to identify blockages or partial obstructions.

 

[djelliott]

I like to strip both carbs together and I use a can of spray carb cleaner to blow through one passage at a time and I compare one carb to the other to identify blockages or partial obstructions.

COOL! That's how I do it too.

 

[VonYinzer]

Welcome to DTT.

All great points^^^^

You should just replace the points. Also, the cover will be chrome (or rusty chrome) not black.

You said you have a manual, well read it from beginning to end. The pics and instructions will give you a good mental picture of whats what.

I generally try to replace all wear items before diving into tuning or whatnot. Points, cables, fuel lines, etc... It suckes when you are almost finished and a cable breaks or something like that.

 

[Teddyjo]

Thanks for the replys and help guys. I think i may have identified a leak in the one carb which might explain the one cylinder acting erratically. I'm going to strip it down and also take a look at the points. Thanks again everyone

 

[Teddyjo]

Todays updates took off the left carb and found this

a tiny gash in the carb right above the float bowl. So i stripped one of my old carbs to just the body cleaned it real good then used the newer parts from the other carb to make a functioning carb. All jets were clear everything seemed functional but when i put it all back together i still couldnt get the bike to start at all. Funny thing is I was holding the electric start button for like 5min minutes praying that it would work again since i was sweating and bam it the electric start turned over. Still no action out of the motor even though I get spark so it has to be a fuel or timing issue.

 

[Ramrod]

How many miles on the bike? I would check your cylinder compression, if you dont have a compression tester, you can buy them pretty cheap. Low compression can indicate a need for new piston rings or valve issues. If you have low compression a common check is to pour a very small amount of oil into the cylinder (via the spark plug hole) and re-check the compression. If it went up then you probably need rings, if it is totally unchanged then you may have valve problems.

Check valve clearance too.